Arrangement for distribution of a pressure medium in a jet loom

ABSTRACT

A normally closed, electrically actuated control valve is interposed between a pressure source and a jet in a jet loom. A pair of fixed pick-up heads are disposed in adjustable angular spaced relation adjacent the periphery of the main shaft of the loom. The heads individually cooperate with an actuator carried on the periphery of the main shaft to respectively emit first and second trigger pulses as the actuator moves past the heads. The first pulse triggers on a first thyristor which responds to open a control valve, and the second pulse triggers on a second thyristor to disable the first thyristor and close the valve. The duration of the fluid flow through the jet, which serves to propel a weft against the shed of the loom, is proportional to the angular spacing between the first and the second heads.

United States Patent Jansa et al.

1 ARRANGEMENT FOR DISTRIBUTION OF A PRESSURE MEDIUM IN A JET LOOM [75] lnventors: Milos Jansa, Brno; Miloslav Bezdek,

Chorvatska Nova Ves; Juraj Spisiak, Brno, all of Czechoslovakia [73] Assignee:

1221 Filed:

[30] Foreign Application Priority Data Jan. 26, 1973 Czechoslovakia 599-73 [52] US. Cl. 139/127 P [51 Int. Cl. D03D 47/30 [58] Field of Search 139/127 R, 127 P, 144; 226/7, 97; 239/410, 411

[56] References Cited UNITED STATES PATENTS 3,828,829 8/1974 Gotoh et al. 139/127 P 6 FLUID SOURCE 6 9 I We f nssY Vyzkumny a vyvojovy ustav Avodu vseobecneho strojirenstvi, Brno, Czechoslovakia Jan. 28, 1974 [2]] Appl. No.: 436,898

Primary Examiner-Henry S. Jaudon 57] ABSTRACT A normally closed, electrically actuated control valve is interposed between a pressure source and a jet in a jet loom. A pair of fixed pick-up heads are disposed in adjustable angular spaced relation adjacent the periphery of the main shaft of the loom. The heads individually cooperate with an actuator carried on the periphery of the main shaft to respectively emit first and second trigger pulses as the actuator moves past the heads. The first pulse triggers on a first thyristor which responds to open a control valve, and the second pulse triggers on a second thyristor to disable the first thyristor and close the valve. The duration of the fluid flow through the jet, which serves to propel a weft against the shed of the loom, is proportional to the angular spacing between the first and the second heads.

7 Claims, 3 Drawing Figures FISSY STFI srop HERD EL 70 PATENTEDSEP 81975 F LU/D SOURCE ARRANGEMENT FOR DISTRIBUTION OF A Y PRESSURE MEDIUM IN A JET LOOM BACKGROUND OF THE INVENTION In the operation of a jet loom a weft thread is selec- 5 tively propelled into the shed of the loom by means of a jet which directs a pressurized fluid against the weft. In existing arrangements of this type initiation and control of the duration of the flow of the fluid from a pres sure source to the jet is provided by means of mechanical sliding valves orpistons, cooperating with a 'surrounding cylinder and disposed physically near the main rotatable shaft of the loom. The piston is typically attached to a cam follower associated with a suitably shaped cam, disposed on the rotatable main shaft of the loom. Such types of sliding valve control means for the fluid flow to the jet have several disadvantages in addition to the mounting difficulties inherent in their required positioning adjacent the main shaft. It has been found, for example, that from 50-70% of the total pressure drop in the fluid delivery system of the loom is due to hydraulic resistance and leaks in the sliding valves. Moreover, while it is possible in such arrangements to vary the duration of fluid flow by adjustment of the length of the piston associated with the sliding valves, such adjustment requires modification of the cam and can not be accomplished while the loom is in operation.

SUMMARY OF THE INVENTION These disadvantages are minimized with the jet loom fluid flow control arrangement of the present invention, which employs in place of the mechanical sliding valves a normally closed electrically actuated valve for selectively directing pressurized fluid from the pressure source to the jet.

In an illustrative embodiment the actuating input of the valve is regulated by a first thyratron-like semiconductive switch that is'associated with a first pick-up head, disposed at a first location adjacent the periphery of the main shaft.

An actuator is carried on the periphery of the main shaft. When such actuator moves past the first pick-up head during each cycle or rotation of the shaft, the first head generates a trigger pulse to enable the first semiconductive switch, which in turn opens the valve, to start the fluid flow to the jets. As the shaft continues to rotate, the actuator moves past a second pick-up head associated with a second semiconductive switch whose transconductive path is disposed in shunt with that of the first switch. The resulting trigger pulse from the second pick-up head turns on the second semiconductive switch to disable the first switch and thereby close the valve.

The time of initiation and the duration of the fluid flow pulse to the jet may be easily varied while the loom is in operation by suitably adjusting the position of the first pick-up head and the angular separation between the first and second pick-up heads.

An added feature of the invention is the provision of an independently actuable auxiliary switch disposed in shunt with the first semiconductive switch for controlling the opening and closing of the valve. Such auxiliary switch may be operated while the loom is at rest to initially propel the first weft thread into the shed prior to loom operation via the same jet employed while the loom is in motion. This avoids an additional disadvantage of present sliding valve control arrangements,

which requirea separate auxiliaryjetand an associated control arrangement to effect the introduction of the firstweft. v if i" dance with the invention, for controlling fluid flow to.

ajet in a jet loom; FIG. 2 is a diagrammatic representation of a-portion of the arrangement of FIG. 1, illustrating the cooperation of a shaft mountedactuator and a pair of pick-up heads for generating trigger pulses; and

FIG. 3 is a combined block schematicv diagram simi lar to FIG. 1, but illustrating details of a portion thereof including a triggerable switch arrangement forelectrically actuating a normally closed fluid control valve.

DETAILED DESCRIPTION Referringnow' 'to the drawing:

FIG. 1 shows schematically a portion 50 of ajet loom for selectively introducing a weft 51 into a shed 52. The introduction of the weft is accomplished by directing, against the weft, pulses of a pressurized fluid from a fluid source 6 via a jet 8. The fluid pulses are generated in synchronism with the rotation of a main shaft 5 of the loom, as indicated below. r

In accordance with the inventiomthe fluid from the source 6 is selectively direc'te'd to the jet -8 by means of a normally closed valve 3. The valve 3 is actuable to an open position via the excitation of 'a"""control 'path 53-53, coupled to a voltage source l0 l0 througha valve operating assembly 2. Y

The assembly2 is coupled to the output ofa'pick-up head assembly 1, which is associated with the shaft 5 'in a manner depicted in FIG. 2. 1

In particular the pick-up assembly includes a start pick-up head 1a and a stop pick-up head lb disposed at selectable first and second locations in angular spaced relation around a path 56 adjacent the periphery of the shaft 5. Both the location of the individual pick-up heads la and 1b, and their angular spacing, are adjustable in a manner shown by arrows57 and 58. The heads 1a and 1b may illustratively co mp'rise contactless thresholdactivated detectors, excited by the voltage source 10 -10 ,(FIG. 3).; 1

An actuator 4 (FIG. 2) is disposed on the periphery of the shaft 5 for rotation therewith. The actuator 4, which may take the form of a projecting arm as shown, cooperates with the pick-up head 1a, whereby the head 1a generates a trigger pulse on an output line 61 thereof when the actuator 4 moves past it during the rotation of the shaft 5. In like manner the actuator 4 cooperates with the head 1b, so that the latter subsequently generates a trigger pulse on an output line 62 when the actuator 4 advances past it. The pulses on the lines 61 and 62 are applied to a valve operating assembly 2 (FIG. 1). As shown in FIG. 3, the assembly 2 includes a first thyratron-like semiconductor switch 20, illustratively a thyristor. whose anode-cathode (transconductive) path is in series with the valve control path 5353 across the power supply terminals l0l0. The transconductive path of a second thyristor 2b which is coupled to the terminals 10-10 through a resistor 2c shunts the transconductive path of the thyristor 2a via a capacitor 2d. i

The output 61 of the head la is coupled to the control electrode of the thyristor 2a. The output 62 of the head 1b is coupled to the control electrode of the thyristor 2b. A manually operable auxiliary switch 9 is coupled across the transconductive path of the thyristor In the operation of the electrically actuated fluid flow control arrangement just described, it-is assumed that the shaft 5 is'initially at rest. ln order to introduce the first weft into the shed via fluid pressure from the jet 8, the auxiliary switch 9 is first manually closed for a desired duration to establish an excitation path from the power supply terminals l0l0 to the valve control path 53-53. This serves to initiate a flow of pressure fluid through the jet 8. After this flow has been established for a desired time to introduce the first weft into the shed, the switch 9 is opened to reclose the valve 3 to stop the fluid flow to the jet. The loom is now turned on to start the rotation of the main shaft 5. At the instant during each resulting cycle of rotation of the shaft at which the actuator 4 moves past the head la, the control electrode of the thyristor 2a is triggered to completean excitation path from the source terminals 10-10 to the valve control path 5353. Once triggered, the switch 29 remains enabled so that the valve stays open to permit pressure flow to the jet 8. As the shaft continues to rotate, the actuator 4 moves past the head lb to excite the control electrode of the switch 2b. The resultant enabling of the switch 2b effectively shunts the switch to disable the latter and thereby to close the valve. The duration of each resulting pulse of fluid is determined for a given angular speed of the shaft 5 by the then selected angular spacing between the heads la and lb.

k In the foregoing the invention has been described in connection with a preferred arrangement thereof. Many variations and modifications will now occur to those skilled in the art. It is accordingly desired that the scope of the appended claims not be limited to the specific disclosure herein contained.

What is claimed is: 1. In a jet loomhaving a shed into which a weft may be propelled by means of the application, through a jet, of a pressure medium supplied from a pressure source, an improved arrangement for selectively applying the pressure medium to the jet, which comprises:

a normally closed valve for interconnecting the pressure source with the jet, the valve being operable to an open condition upon the excitation of a control input thereof; first normally disabled switching means operable when enabled for exciting the control input of the valve to open the valve;

an actuator cooperable with the first switching means for enabling the first switching means when the actuator is moved past the first switching means; and

means for cyclically moving the actuator past the first switching means to enable the first switching means.

2. An arrangement as defined in claim I, in which the arrangementfurther comprises an auxiliary switch connected in shunt with the first switching means and operable independently of the first switching means to effect the propulsion of an initial weft thread into the shed.

3. An arrangement as defined in claim 1, in which the arrangement further comprises second switching means operable when enabled for disabling the first switching means, the second switching means being cooperable with the actuator so that the latter enables the second switching means when the actuator is moved past the second switching means; and in which the moving means are arranged to move the actuator successively past the first and second switching means.

4. An arrangement as defined in claim 3, in which the arrangement further comprises a rotatably mounted main shaft; in which the first switching means comprises a first pick-up head disposed at a first location adjacent the periphery of the main shaft; in which the second switching means comprises a second pick-up head disposed at a second location adjacent the periphery of the main shaft in spaced angular relation to the first location; and in which the moving means comprises means for mounting the actuator on the periphery of the main shaft, the first and second pick-up heads being arranged to individually generate trigger pulses when the main shaft rotates the actuator past the respective pick-up heads.

5. An arrangement as defined in claim 4, in which the arrangement further comprises means for adjusting the angular spacing of the first and second locations.

6. An arrangement as defined in claim 4, in which the first switching means further comprises, in combination, a first thyratron-like semiconductive device having a control electrode and a transconductive path serially connected between a power source and the control input of the valve, and means for coupling the output of the first pick-up head to the control electrode of the first semiconductive device.

7. An arrangement as defined in claim 6, in which the second switching means comprises, in combination, a second thyratron-like semiconductive device having a control electrode and a transconductive path coupled across the transconductive path of the first semiconductive device, and means for coupling the output of the second pick-up head to the control electrode of the second semiconductive device. 

1. In a jet loom having a shed into which a weft may be propelled by means of the application, through a jet, of a pressure medium supplied from a pressure source, an improved arrangement for selectively applying the pressure medium to the jet, which comprises: a normally closed valve for interconnecting the pressure source with the jet, the valve being operable to an open condition upon the excitation of a control input thereof; first normally disabled switching means operable when enabled for exciting the control input of the valve to open the valve; an actuator cooperable with the first switching means for enabling the first switching means when the actuator is moved past the first switching means; and means for cyclically moving the actuator past the first switching means to enable the first switching means.
 2. An arrangement as defined in claim 1, in which the arrangement further comprises an auxiliary switch connected in shunt with the first switching means and operable independently of the first switching means to effect the propulsion of an initial weft thread into the shed.
 3. An arrangement as defined in claim 1, in which the arrangement further comprises second switching means operable when enabled for disabling the first switching means, the second switching means being cooperable with the actuator so that the latter enables the second switching means when the actuator is moved past the second switching means; and in which the moving means are arranged to move the actuator successively past the first and second switching means.
 4. An arrangement as defined in claim 3, in which thE arrangement further comprises a rotatably mounted main shaft; in which the first switching means comprises a first pick-up head disposed at a first location adjacent the periphery of the main shaft; in which the second switching means comprises a second pick-up head disposed at a second location adjacent the periphery of the main shaft in spaced angular relation to the first location; and in which the moving means comprises means for mounting the actuator on the periphery of the main shaft, the first and second pick-up heads being arranged to individually generate trigger pulses when the main shaft rotates the actuator past the respective pick-up heads.
 5. An arrangement as defined in claim 4, in which the arrangement further comprises means for adjusting the angular spacing of the first and second locations.
 6. An arrangement as defined in claim 4, in which the first switching means further comprises, in combination, a first thyratron-like semiconductive device having a control electrode and a transconductive path serially connected between a power source and the control input of the valve, and means for coupling the output of the first pick-up head to the control electrode of the first semiconductive device.
 7. An arrangement as defined in claim 6, in which the second switching means comprises, in combination, a second thyratron-like semiconductive device having a control electrode and a transconductive path coupled across the transconductive path of the first semiconductive device, and means for coupling the output of the second pick-up head to the control electrode of the second semiconductive device. 